This project investigates the impact of an initiative to provide "treatment on demand" to persons seeking publicly funded drug abuse treatment in San Francisco. The proposal represents a collaboration between the University of California, San Francisco, and the San Francisco Department of Public Health's Community Substance Abuse Services. The San Francisco treatment on demand initiative is one of the first of its kind in the country. It signals growing awareness of the human and economic costs of substance abuse to communities, and reflects an increasing political will to address these costs by increasing access to treatment. These driving concerns reflect national trends as communities across the country apply innovative strategies to address the drug abuse treatment needs of indigent or uninsured persons. The proposed project will determine whether the treatment on demand initiative is associated with changes in access to treatment, whether it is associated with changes in treatment capacity and utilization patterns, and assess the economic consequences of the initiative for the treatment system, society, and various service payers. The long-term goal of the project is to define the treatment on demand initiative as it is implemented in San Francisco, to determine key system-level impacts of this unique public health effort to address chronic substance abuse treatment needs, and to disseminate findings to federal, state, and local policymakers, and in the scientific literature.